THz-driven acceleration——A new way to start compact accelerator

Terahertz (THz)-driven electron acceleration is now an emerging direction for developing compact high-brightness particle accelerators. Following the experimental demonstration of THz acceleration by Nanni et al in 2015, great progress has been made in the development of THz-driven electron guns, THz-driven acceleration, and THz-based beam manipulation and diagnostics. Research activities related to the physics and technology of THz acceleration are being actively pursued worldwide. Several compact accelerators based on this unique technology have been proposed and are now under construction. This review will focus on the development of THz-driven electron acceleration over the past decades as well as its technical challenges and related applications.